System, Method and Apparatus for Asynchronous Communication in Wireless Sensor Networks

Abstract

The present invention provides a system, method and apparatus for asynchronous communication in wireless sensor networks. Each sensor includes a transmitter normally operating in a sleep mode, a low power receiver having a memory, a sensing module, and a processor normally operating in a sleep mode communicably coupled to the transmitter, the low power receiver and the sensing module. Data is received via the low power receiver and stored in the memory. Whenever a wakeup time occurs, the transmitter and the processor are put in an operational mode, sensory data is obtained from the sensing module, the sensory data is processed, the received data is obtained from the low power receiver memory, the processed sensory data and the received data are transmitted via the transmitter, and the transmitter and the processor are put in the sleep mode.

1 . A method for communicating within a wireless network of sensors wherein each sensor comprises a transmitter normally operating in a sleep mode, a low power receiver having a memory, a sensing module, a processor normally operating in a sleep mode communicably coupled to the transmitter, the low power receiver and the sensing module, the method comprising the steps of:
 receiving data via the low power receiver;   storing the received data in the memory; and   whenever a wakeup time occurs, putting the transmitter and the processor in an operational mode, obtaining sensory data from the sensing module, processing the sensory data, obtaining the received data from the low power receiver memory, transmitting the processed sensory data and the received data via the transmitter, and putting the transmitter and the processor in the sleep mode.   
   
   
       2 . The method as recited in  claim 1 , wherein the sensor determines the wakeup time without synchronization with the wireless network or one or more local sensors. 
   
   
       3 . The method as recited in  claim 1 , wherein the sensor further comprises:
 a transceiver that includes the transmitter, the low power receiver and another receiver normally operating in the sleep mode; and   wherein the low power receiver is a module within the other receiver that is capable of being disabled such that the transceiver, the other receiver and the processor are put in the operational mode.   
   
   
       4 . The method as recited in  claim 1 , wherein the steps of receiving the data and storing the received data occur while the transmitter and the processor are in the sleep mode. 
   
   
       5 . The method as recited in  claim 1 , further comprising the step of performing one or more initialization functions wherein the initialization function(s) comprise a neighbor and route discovery, a synchronization, a cluster formation, or a localization. 
   
   
       6 . The method as recited in  claim 1 , further comprising the step of performing one or more data processing functions wherein the data processing function(s) comprise a minimum and maximum calculation, an average calculation, a summation calculation, a count, a data compression, a target detection, a classification, a tracking function, an adaptive scheduling function or a collaborative signal processing function. 
   
   
       7 . The method as recited in  claim 1 , further comprising the step of determining the wakeup time randomly, based on a coordinated wakeup schedule, or an interleaved wakeup schedule. 
   
   
       8 . The method as recited in  claim 1 , further comprising the step of filtering the received data. 
   
   
       9 . The method as recited in  claim 1 , wherein an acknowledgement is transmitted to a source of the received data during the wakeup time. 
   
   
       10 . The method as recited in  claim 1 , further comprising the step of changing the wakeup time whenever a collision is detected. 
   
   
       11 . The method as recited in  claim 10 , wherein the collision is detected whenever consecutive acknowledgements are not received, one or more data reports are not received, or a combination thereof. 
   
   
       12 . A computer program embodied on a computer readable medium for communicating within a wireless network of sensors wherein each sensor comprises a transmitter normally operating in a sleep mode, a low power receiver having a memory, a sensing module, a processor normally operating in a sleep mode communicably coupled to the transmitter, the low power receiver and the sensing module, the computer program comprising:
 a code segment for receiving data via the low power receiver;   a code segment for storing the received data in the memory; and   a code segment for whenever a wakeup time occurs, putting the transmitter and the processor in an operational mode, obtaining sensory data from the sensing module, processing the sensory data, obtaining the received data from the low power receiver memory, transmitting the processed sensory data and the received data via the transmitter, and putting the transmitter and the processor in the sleep mode.   
   
   
       13 . A sensor comprising:
 a transmitter normally operating in a sleep mode;   a low power receiver having a memory that receives data and stores the received data in the memory;   a sensing module;   a processor normally operating in a sleep mode communicably coupled to the transmitter, the low power receiver and the sensing module; and   whenever a wakeup time occurs, the transmitter and the processor are put in an operational mode, sensory data is obtained from the sensing module, the sensory data is processed, the received data is obtained from the memory, the processed sensory data and the received data are transmitted via the transmitter, and the transmitter and the processor are put in the sleep mode.   
   
   
       14 . The sensor as recited in  claim 13 , wherein the sensor determines the wakeup time without synchronization with the wireless network or one or more local sensors. 
   
   
       15 . The sensor as recited in  claim 13 , wherein the sensor further comprises:
 a transceiver that includes the transmitter, the low power receiver and another receiver normally operating in the sleep mode; and   wherein the low power receiver is a module within the other receiver that is capable of being disabled such that the transceiver, the other receiver and the processor are put in the operational mode.   
   
   
       16 . The sensor as recited in  claim 13 , wherein the wakeup time is determined randomly, based on a coordinated wakeup schedule, or an interleaved wakeup schedule. 
   
   
       17 . The sensor as recited in  claim 13 , wherein the received data is filtered. 
   
   
       18 . The sensor as recited in  claim 13 , wherein an acknowledgement is transmitted to a source of the received data during the wakeup time. 
   
   
       19 . The sensor as recited in  claim 13 , wherein the wakeup time is changed whenever a collision is detected. 
   
   
       20 . The sensor as recited in  claim 19 , wherein the collision is detected whenever consecutive acknowledgements are not received, one or more data reports are not received, or a combination thereof. 
   
   
       21 . A sensor network comprising:
 a sink node;   two or more sensors forming a wireless communications network with the sink node; and   wherein each sensor comprises a transmitter normally operating in a sleep mode, a low power receiver having a memory that receives data and stores the received data in the memory, a sensing module, a processor normally operating in a sleep mode communicably coupled to the transmitter, the low power receiver and the sensing module, and whenever a wakeup time occurs, the transmitter and the processor are put in an operational mode, sensory data is obtained from the sensing module, the sensory data is processed, the received data is obtained from the memory, the processed sensory data and the received data are transmitted via the transmitter, and the transmitter and the processor are put in the sleep mode.   
   
   
       22 . The sensor network as recited in  claim 21 , wherein the sensor determines the wakeup time without synchronization with the wireless network or one or more local sensors. 
   
   
       23 . The sensor network as recited in  claim 21 , wherein the sensor further comprises:
 a transceiver that includes the transmitter, the low power receiver and another receiver normally operating in the sleep mode; and   wherein the low power receiver is a module within the other receiver that is capable of being disabled such that the transceiver, the other receiver and the processor are put in the operational mode.   
   
   
       24 . The sensor network as recited in  claim 21 , wherein the wakeup time is determined randomly, based on a coordinated wakeup schedule, or an interleaved wakeup schedule. 
   
   
       25 . The sensor network as recited in  claim 21 , wherein the received data is filtered. 
   
   
       26 . The sensor network as recited in  claim 21 , wherein an acknowledgement is transmitted to a source of the received data during the wakeup time. 
   
   
       27 . The sensor network as recited in  claim 21 , wherein the wakeup time is changed whenever a collision is detected. 
   
   
       28 . The sensor network as recited in  claim 27 , wherein the collision is detected whenever consecutive acknowledgements are not received, one or more data reports are not received, or a combination thereof.